1. Field of the Invention
The present invention relates to an image compression apparatus which compresses image data.
2. Description of the Related Art
There is an apparatus such as a copying machine or a printer which handles document images, performs image compression on the document images using an image compression apparatus, and then stores or transfers the compressed document images.
Recently, technological improvements in a scanner apparatus or a printer apparatus that handles document images has led to a demand for the image compression apparatus included in an image processing apparatus connected to such an apparatus, to process image data of higher resolution. At the same time, there is a demand for such an image compression apparatus to continue processing image data of low resolution as previously. It is thus necessary for the image compression apparatus to support image data of various resolutions.
Further, a level of visual image quality deterioration caused by performing image compression is different depending on the resolution of the image data. To solve such a problem, Japanese Patent Application Laid-Open No. 08-149282 discusses an image compression apparatus that compresses the image data by determining a compression rate according to the resolution. As a result, the difference between the levels of image quality deterioration caused by performing image compression due to the differences in the resolution of the image data is decreased.
On the other hand, since the image compression apparatus is to process image data of high resolution in which there is a large number of pixels, a circuit size thereof becomes large. Cost of semiconductor manufacturing and power consumption thus increase in such an image compression apparatus.